少层锑烯的微波快速剥离和储钾机制研究

Due to the abundant potassium metal reserves and low standard reduction potential, the development of potassium ion batteries (PIBs) shows great potential for energy storage systems. Alloying-type antimony (Sb) anode materials have been extensively studied because of their low cost and high capacity. In order to address the issue of slow diffusion kinetics and large volume expansion during charge and discharge of untreated bulk Sb anode, this project aims to use microwave-assisted liquid phase exfoliation to prepare high-quality antimonene (new graphene-like two-dimensional (2D) materials). Further, a layer-by-layer self-assembled antimonene-graphene composite electrode material can be designed by using secondary ion intercalation and other chemical strategies. The combination of high specific area of 2D antimonene, the high conductivity of graphene and the confinement nature of self-assembled structure is expected to endow the as-fabricated PIBs anode material with high energy density, high rate performance and excellent stability. Through advanced in-situ characterization techniques (XRD, TEM, Raman), the evolution of electrode interface and material microstructure during charge and discharge process can be monitored in real time, thus to disclose its intrinsic potassium storage mechanism. On the basis of the experimental and analytical results, the electrode structure will be further optimized with regards to higher-performance PIBs. In addition, the key scientific issues namely the preparation of new-type 2D antimonene materials with large area, few defects and adjustable band gaps by ultrafast microwave exfoliation are of great significances towards the practical application for major cross-cutting fronts of optoelectronic devices, superconducting materials and topological materials.

由于钾金属储量丰富、标准还原电势较低，钾离子电池新型储能体系开发具有广阔前景。合金化类锑基等负极材料因其低成本、高容量得到广泛研究。针对传统锑基负极材料扩散动力学缓慢、充放电过程中体积膨胀大等关键科学问题，本项目拟采用微波辅助液相快速剥离制备高品质少层锑烯（类石墨烯新型二维材料），进一步采用二次离子插层等策略，设计层层自组装锑烯-石墨烯复合柔性电极材料。结合二维锑烯材料高比面积、石墨烯高导电率等特点以及自组装结构限域优势，以期实现高能量密度、高倍率性能且稳定性优异的钾离子电池负极材料。通过先进原位表征技术（XRD、TEM、Raman），实时监控电极表界面及材料微结构在充放电过程中的演变规律，揭示储钾机理并在此基础上优化电极材料设计。此外，本项目拟开发的微波快速剥离制备大面积、缺陷少、能带间隙可调控的新型锑烯二维材料，对光电器件、超导及拓扑材料等交叉前沿的基础研究和实际应用具有重要意义。

由于钾金属储量丰富、标准还原电势较低，开发新型高能量密度、高倍率性能且稳定性优异的钾离子电池负极材料是钾离子电池研发的科学难点和重要挑战。然而钾离子较大尺寸效应，使得电极材料在循环过程中经历巨大体积膨胀，从而造成电极与集流体脱落并进一步引起容量快速下降和性能衰退。因此开发采用二次离子插层等策略，设计层层自组装复合柔性电极材料对钾离子电池的发展具有重要的现实意义和经济意义。.本项目在2020年至2022年设计开发了多种储钾材料，并系统研究了其作为钾离子电池负极材料时的储钾性能与存储机制，相关代表工作如下：.（1）通过溶胶-凝胶法结合酸蚀处理将还原氧化石墨烯改性为均匀的少层结构。石墨烯（CNCG）构建的化学交联和机械增强碳网络表现出优异的电化学和力学性能。作为自支撑钾离子电池负极材料（~7mg·cm-2），实现了CNCG在50mA·g−1的电流密度下提供317.7mAh·g−1的高可逆比容量和循环稳定性（在50mA·g−1下500次循环后为208.4mAh·g−1）。.(2)红磷（RP）由于体积膨胀和电子导电性差，表现出急剧的容量衰减和结构坍塌。因此设计一种体积应变弛豫电极结构，通过将限制的非晶RP封装在3D互连的硫、氮共掺杂的碳纳米纤维（RP@S-N-CNFs）中。作为KIB的阳极时，RP@S-N-CNFs电极具有高可逆容量（在0.1A·g−1下循环100次后为566.7mAh·g−1）和稳定性（在2A·g−1下循环2000次后为282mAh·g−1）。.（3）通过使用价格低廉、来源广泛的对甲苯磺酸钠(CH3C6H4SO3Na)为原料，采用碳化法合成了双硫掺杂碳纳米片（DS-CN）。纳米片具有较大的层间距(4.25Å)，利于K+插入。C-S键和嵌入式超细硫酸盐提供了活性位点，以提高容量和加速动力学。较高S/O比可以减少氧官能团引起的不可逆反应。高可逆比容量(在50mA·g-1下有331.9mAh·g-1)，良好的倍率性能（在1000mA·g−1有165.3mAh·g−1）。和长循环稳定性（每个循环0.011%的容量衰减）归因于非原位XPS和电化学分析证实了层间距扩大的C-S键与K+之间的反应以及更活跃的-C-SO2-键之间的多重协同效应。.本项目对纳米电池材料剥离及生长机制和储钾机制研究提供了重要的科学依据。

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